JPH07159776A - Reflection type liquid crystal display device - Google Patents

Abstract

PURPOSE:To make a device hardly influenced by external scattered light in the active matrix type reflection type liquid crystal display device which is a guest host type or a high molecular dispersed type and where a reflection plate and picture element electrode is installed. CONSTITUTION:This device is provided with a nearly rectangular-shaped reflection plate and picture element electrode 23 constituted of aluminum on a grid- shaped auxiliary capacitance electrode 17 through interlayer insulating film 19. Therefore, the surface of the picture element electrode 23 serving also as the reflection plate is rugged corresponding to the grid-shaped auxiliary capacitance electrode 17. Consequently, the intensity of reflected light reflected by the surface of the reflection plate and picture element electrode 23 is uniformly dispersed, so that the device is made hardly influenced by the external scattered light.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflective liquid crystal display device.

[0002]

2. Description of the Related Art Some guest-host type or polymer-dispersed reflective liquid crystal display devices have a reflective plate provided in a cell without using a polarizing plate. In this case, as the display medium, a liquid crystal (guest) mixed with a dye (host) is used as a display medium, and a polymer dispersion type liquid crystal is mixed with a monomer and annealed to obtain a monomer. The polymer is used to polymerize. In the case of an active matrix type, there is a reflective plate in the cell which is also used as a pixel electrode. Then, the external light is reflected as it is by the mirror surface formed of the surface of the reflection plate and the pixel electrode.

[0003]

However, in such a conventional reflection type liquid crystal display device, since the reflector plate and the pixel electrode are flat, when the external light is reflected as it is by the flat mirror surface of the surface. In addition, there is a problem in that the display quality is deteriorated because it is easily affected by the external scattered light, a nearby object is reflected, and the reflected light is colored due to diffraction or interference. An object of the present invention is to provide a reflective liquid crystal display device that can be made less susceptible to the influence of externally scattered light.

[0004]

According to the present invention, the surface of the reflector / pixel electrode is made uneven.

[0005]

According to the present invention, since the surface of the reflection plate / pixel electrode has an uneven shape, the intensity of the reflected light reflected by this surface can be dispersed uniformly, and as a result, the influence of external scattered light can be reduced. You can make it hard to receive.

[0006]

1 (A) and 1 (B) show the essential parts of a reflective liquid crystal display device according to an embodiment of the present invention. This reflection type liquid crystal display device is of an active matrix type and has a common electrode panel 2 on a display drive panel 1.
Are stacked via a spacer (not shown), and the liquid crystal 3 is enclosed between them. The liquid crystal 3 referred to here means a liquid crystal (guest) mixed with a dye (host) in the case of a guest-host type, and a liquid crystal mixed with a monomer in the case of a polymer dispersion type. And then annealed to polymerize the monomer to form a polymer.

The display drive panel 1 has a glass substrate 11. A semiconductor thin film 13 made of amorphous silicon or polysilicon forming a part of a thin film transistor (switching element) 12 is formed at a predetermined position on the upper surface of the glass substrate 11, and a gate insulating film made of silicon oxide or the like is formed on the entire upper surface. The film 14 is formed. The gate electrode 1 is formed at each predetermined position on the upper surface of the gate insulating film 14.
5, a gate line 16 connected to the gate electrode 15, a grid-shaped auxiliary capacitance electrode (lower layer) 17, and an auxiliary capacitance line 18 connected to the auxiliary capacitance electrode 17 are formed of aluminum, and silicon nitride is formed on the entire upper surface thereof. An interlayer insulating film 19 made of, for example, is formed. Interlayer insulation film 1
At a predetermined position on the upper surface of 9, a drain electrode 20, a drain line 21 connected to the drain electrode 20, a source electrode 22, and a substantially rectangular reflector / pixel electrode 23 connected to the source electrode 22 are respectively formed of aluminum. Is formed by. In this case, since the reflector / pixel electrode 23 is formed on the upper surface of the interlayer insulating film 19 covering the grid-shaped auxiliary capacitance electrode 17, the surface thereof has an uneven shape corresponding to the grid-shaped auxiliary capacitance electrode 17. Has become. The drain electrode 20 and the source electrode 22 are connected to the semiconductor thin film 13 via contact holes.

The common electrode panel 2 has a glass substrate 31. A common electrode 32 made of ITO is formed on the lower surface of the glass substrate 31. Then, the pixel capacitance unit is configured by the reflective plate / pixel electrode 23, the common electrode 32, and the liquid crystal 3 therebetween. In addition, the reflective plate / pixel electrode 23, the auxiliary capacitance electrode 17, and the interlayer insulating film 19 between them.
The auxiliary capacitance section is configured by the above.

As described above, in this reflection type liquid crystal display device, the surface of the reflection plate / pixel electrode 23 has an uneven shape corresponding to the grid-shaped auxiliary capacitance electrode 17, and therefore the intensity of the reflected light reflected by this surface. Can be uniformly dispersed. As a result, it is possible to reduce the influence of externally scattered light, and it is possible to improve the display quality without causing reflection of nearby objects or coloring of reflected light due to diffraction or interference. You can Further, since the uneven shape of the surface of the reflection plate / pixel electrode 23 corresponds to the grid-shaped auxiliary capacitance electrode 17 provided therebelow, it is possible to simply form the reflection plate / pixel electrode 23.
The surface of the reflective plate / pixel electrode 23 can be formed in a grid-like concavo-convex shape. Further, since the auxiliary capacitance electrode 17 is provided below the reflection plate / pixel electrode 23, even if the auxiliary capacitance electrode 17 is provided over a wide range of the entire opening, the auxiliary capacitance electrode 17 does not reduce the aperture ratio. Can be

In the above embodiment, the auxiliary capacitance electrode 17 is used.
Are formed in a lattice shape and the surface of the reflector / pixel electrode 23 has a shape corresponding thereto. However, not limited to this, for example, the auxiliary capacitance electrode 17 is in a mosaic shape, and the surface of the reflector / pixel electrode 23 has a shape corresponding thereto. May be Further, in the above embodiment, the thin film transistor 12 is used as the switching element.
However, MIM or the like may be used instead of this.

[0011]

As described above, according to the present invention, since the surface of the reflection plate / pixel electrode has an uneven shape, the intensity of the reflected light reflected by this surface can be dispersed uniformly. As a result, it is possible to reduce the influence of externally scattered light, and it is possible to improve the display quality without causing a nearby object to be reflected and the reflected light being colored due to diffraction or interference. it can.

[Brief description of drawings]

FIG. 1A is a plan view of an essential part of a reflective liquid crystal display device according to an embodiment of the present invention, and FIG. 1B is a sectional view taken along line BB thereof.

[Explanation of symbols]

 12 Thin film transistor (switching element) 17 Auxiliary capacitance electrode (lower layer) 23 Reflector and pixel electrode

Claims (4)

[Claims] 1. A reflection type liquid crystal display device comprising a reflection plate / pixel electrode, wherein the surface of the reflection plate / pixel electrode has an uneven shape. 2. The reflection type liquid crystal display device according to claim 1, wherein a switching element is provided for each of the reflection plate and the pixel electrode. 3. The reflection type according to claim 1, wherein the uneven shape of the surface of the reflector / pixel electrode corresponds to a lattice-like lower layer provided below the reflector / pixel electrode. Liquid crystal display device. 4. The reflective liquid crystal display device according to claim 3, wherein the lower layer is an auxiliary capacitance electrode.